This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The objective of this study is to quantify cold sensory threshold and tolerance using the cold pressor test in chronic pain patients on chronic opioids and compare them to controls with chronic pain who are not are opioids.